Wacky TimingI am running a '60 Cadillac in my Allard and just installed a Joe Hunt self-contained electronic ignition (magneto look-alike). The timing light shows 10 degrees initial and sounds right, but when I run up the rpm, the light goes way past my mark at 32 degrees, all the way up to 170 or 180 degrees. That's an impossible place for the engine to run. I reviewed an old Sears Timing Light Instruction Sheet and as suggested, moved the pickup on the wire to plug No. 1 as close to the distributor as possible. The advance at rpm then went up to 50 or 60 degrees. I got the same result with two different digital timing lights. Joe Hunt Tech states that there is 22 degrees centrifugal in the distributor, period, and that advance is not adjustable. Why am I getting these inaccurate readings? How can I get an accurate reading?
David Watson
Lititz, PA

2/4This Tony Baron-built 59A Ford flathead V-8 is also destined for an Allard that competes in vintage sports car racing. The aluminum Baron heads and Tom Roberts front cover are OK, but per the rules, the 245hp/280-lb-ft mill is sparked by an old-school mag. Want old-school looks with modern high-output spark? Consider Joe Hunt's electronic distributor.

Don't use a digital timing light. Most digital dial-back timing lights (typically identified by an LED readout) are notoriously inaccurate when used with solid-core plug wires, as well as with many high-output aftermarket ignition systems (MSD being a prime example). Apparently, the digital lights get confused by random electrical-pulse bleed-over. Westech Performance, which does a lot of HOT ROD's dyno testing, has encountered this problem before. It suggests using either an older-style analog dial-back light (usually identified by a regular dial on its back face instead of the LED) or a basic nondial-back light. Westech uses the following two lights, both of which it says have been proven reliable even with the most extreme high-output ignition systems: an old Sears Craftsman Model 21023 with a rotary dial or (for nondial-back usage) MSD's PN 8990. To prevent false triggering with any timing light, it's always good practice to keep the No. 1 cylinder wire well separated from other spark plug wires and to make sure the wires to the timing light's inductive pickup also do not pass near any of the plug wires.

Displacement Vs. TorqueWhat is the relationship between engine displacement and peak torque rpm? For example, if I have a strong but well-mannered V-8 and increase its displacement with a stroker kit, what is going to happen to the shape and placement of the torque curves? For the purpose of this example, all other aspects-including the cam, heads, intake manifold, headers, compression ratio, and so on-remain the same. I am not asking about any increases-just where it will move in the rpm range (if at all).

I think the peak is going to move to a lower rpm with more displacement. My reasoning is that the increased displacement will increase the airflow through the intake manifold, which would increase the cylinder filling at a lower rpm. But the increased airflow would also increase the restriction, and it would hit its flow limit at a lower rpm as well. The result is, while the bigger engine will probably be making more power at a high rpm compared with the smaller-displacement version, it would be starting on the downward side of its power curve earlier as well.
Mike Peissner
San Diego, CA

In general, a normally aspirated engine's torque potential is very closely tied to its displacement. If the engine is not cylinder head limited, as swept volume increases, there should be more cylinder filling on the intake stroke and therefore more thrust on the piston during the power stroke, generating additional torque. If the displacement increase does not translate into a torque increase, the engine is probably being held back in the cam or cylinder head department.

On a typical dual-purpose hot rod engine, if the stroke changes but overall engine displacement remains the same (by decreasing bore diameter), the amount of torque at the peak won't change significantly. But the short-stroke engine's torque peak will usually occur at a higher rpm. Because horsepower is a function of torque output times rpm, if the heads and cam are not otherwise a limiting factor, the short-stroke engine should have a higher top end power potential, albeit at the expense of the extreme bottom end.

Keeping these basics in mind, let's examine your hypothetical case of two engines of different displacement where any displacement change is solely by means of a change in stroke and all other aspects remain the same. In reality, not all aspects can remain the same: Rod length and/or piston compression distance, as well as rotating assembly weight, will also change within the same engine block from any change in stroke. To max out an engine's capabilities, the base cam event timing versus the stroke, the rod length, and the head characteristics would also most likely change. For example, even if only the piston pin location is altered to accommodate the stroke increase without changing the piston skirt's overall shape, the piston ends up dropping further out of the bottom of the cylinder bore at bottom dead center (BDC). This could negatively impact piston stability, increasing piston rock, which in turn may call for additional piston-to-bore clearance. But for the purposes of this comparison, we'll assume all this stuff remains the same.

Dave Ebbert of DNE Motorsports Development has some old-school, DOS-based, analysis software that he says models with a high confidence level what happens due to a stroke change. He ran two cases for me: a small-block and a big-block. One cautionary note is that as stroke increases, so does the rotating assembly's mass engine speed. For any rotating assembly, there is a max safe theoretical rotating assembly rpm, the point at which what Ebbert terms the critical tension number is reached, when the loads imparted to the rotating assembly exceed 4,350 g (4,350 times the force of gravity). Peak tension always occurs at TDC because of the reversal of load. Above this point, even with very good parts, things tend to fly apart (such as the caps pulling off the connecting rod). The torque and power must peak below the critical tension rpm or the engine won't live long and prosper.

The small-block model compares a 355 Chevy (4.030-inch bore x 3.48-inch stroke) with a 383 Chevy (4.030-inch bore x 3.75- inch stroke). It assumes a 10:1 compression ratio, 5.7-inch center-to-center connecting rods, intake ports that flow 240 cfm at 28 inches of water, and a generic flat-tappet cam. As can be seen from the accompanying table, the total torque output increased by more than 30 lb-ft, with the torque peak point occurring about 400 rpm lower. Both engines made nearly the same power but at different rpms. With the longer stroke, the torque and power peaks moved close together.

At this point, a professional engine builder assembling the long-stroke combination would try to reduce engine friction and/or move more air through the engine by changing the cam timing and cylinder head to maintain the original power peak rpm point, assuming that rpm point is not the same as the critical tension rpm (which it isn't here). If by swapping parts, the builder can maintain the same power peak rpm, the long-stroke engine would ultimately make more power.

The big-block Chevy model compares a 467ci Rat (4.310-inch bore x 4.00-inch stroke) with a 496 (4.310-inch bore x 4.250-inch stroke), using 10:1 compression, heads with intake ports that flow about 270 cfm at 25 inches of water, and a generic flat-tappet cam. The long-stroke engine peaked around 300 rpm lower, producing about 35 lb-ft more torque at that point. Total power output was again nearly the same, but the point at which peak power occurs dropped about 350 rpm lower on the long-stroke engine.

Additional sims indicate that throwing ever-larger heads on a 467 still won't get its torque peak number up to the 496's level, confirming that torque potential is closely tied to displacement. The bigger heads move the torque peak to a higher rpm, which increases horsepower at the expense of low-end driveability. Conversely, getting the 496's torque peak to occur at the same rpm as the original 280-cfm head on the 468 is doable by installing a head with 290-cfm intake port flow-which again also raises the top-end power.

The Mutt RevisitedI am building a Ford 351C using some of the details from the web-posted article "The Mutt" as a guide. I am going with a hydraulic roller lifter cam but am concerned with using the Ford Racing roller lifter specified on the buildsheet. I spoke to Ford Racing, and the company indicated that this lifter will not line up correctly with the Cleveland oil passage. Did you find this to be a problem, or did you have to make modifications?
Eric Schisler
St. Charles, IL

The advantage of using a factory-style hydraulic-roller lifter retained by a valley hold-down plate (aka the spider) is that these mass-production items are widely available and much less expensive than retrofit-style aftermarket paired guidebar-style lifters. In the case of Ford specifically, the downside is that factory Ford 5.0L/5.8L Windsor small-blocks intended for use with factory hydraulic roller lifters and cams have taller lifter bosses than previous Ford small-blocks to fully support the taller factory hydraulic-roller lifters. The new lifter's oil groove and hole are located higher up on the lifter body than the original flat-tappet configuration or the retrofit aftermarket guidebar-style roller lifter. Installing the factory roller lifters in preroller-cam factory blocks running larger cams ground on the stock base circle could cause the lifter to rise so high in the boss that its oil hole is uncovered. There are no OEM Cleveland or Modified blocks with the taller lifter bosses, as production of that engine family ended long before factory roller cams were introduced. The premium, most bulletproof solution is stepping up to the pricey aftermarket retrofit-paired guidebar lifters (such as Comp Cams PN 8931-16).

To use the more economical factory OEM-style lifters (such as Comp PN 851-16) with a spider-and-guide retrofit kit (Comp PN 31-1000), you'll need to have the cam ground on a reduced base circle. This is what KT Engines did on "The Mutt" buildup. Because on a reduced-base-circle cam the lifter starts out lower in the lifter bore, the lifter's oil groove won't rise out the top of the bore at full lift. The downside is that valvetrain geometry requires correction with an adjustable valvetrain and custom-length pushrods, which will have to be determined during initial engine mockup. There are also theoretical durability issues: A reduced-base-circle cam billet is thinner, so there's more core flex and each lobe sees higher point and pressure loading. The stock Ford cam base circle is larger than the small-block Chevy, which in theory makes a Ford cam stronger and also permits grinding quicker lobe profiles not otherwise obtainable on a Chevy; so, again in theory, by reducing the base circle, you are giving up some of the supposed advantages of a Ford over a Chevy. In the non-pro-racer world, these are not critical issues. Remember, too, that really big-lift, full-race cams must be ground on a reduced base circle so they can physically fit through the block's cam journal bores.

There have been some changes since the "The Mutt" article was written. Crane Cams has reorganized and currently sells only motorcycle parts. Ford Cleveland heads flow much better on the intake than the exhaust, so a dual-pattern grind is preferable to the originally specified 234-degree-duration, single-pattern cam. Consider a Comp Cams custom profile based on its SFI lobe series: No. 3016 for the intake side (230 degrees duration at 0.050, 0.612-inch valve lift with 1.7:1 rockers); No. 3037 on the exhaust (236 degrees duration, 0.607-inch lift). For a carbureted engine, have the cam ground on a 110-degree LSA and install it 4 degrees advanced (106-degree intake centerline).

I'm told Cleveland hydraulic roller cams have become popular enough that (unless otherwise specified) it's now standard practice at Comp to grind them all on a reduced base circle to avoid any potential problems-but it never hurts to make sure when ordering that it's indeed the case. In Comp's nomenclature, if ordering a custom-ground Ford cam, appending an "S" to the lobe profile (as in 3016S) specifies a reduced base circle cam; an "F" suffix would designate a standard, nonreduced base circle.

Meanwhile, KT Engines continues to refine the basic 400M-based engine package. Instead of using the originally specified Chrysler 340 pistons and small-block Chevy connecting rods, it says it now prefers an Eagle 4.25-inch stroker crank for a 351W Ford/400M-size main journals and Chevy 2.1-inch rod journals, Eagle Chevy LS1 rods with up to a 6.560-inch center-to-center length, and KT's own custom piston or a Diamond Racing Boss 302 piston (typically, with about a 1.600-inch piston compression distance with a 6.560-length rod in a 400M block). The Eagle crank drops right into a 351M/400 block, and the lightweight unit is internally balanced. On a 4.040-inch bore 400M, displacement moves up to 436 ci (instead of 431 ci with the previous 4.2-inch stroke). The Eagle LS1 rod has a stronger beam, is lighter, and clears everything better. Similar big strokers can also be built up from 351C or 351W blocks using Eagle cranks and rods with custom pistons. Contact KT Engines for further information on these refined combos.

Another drawback of the original buildup was the 400M-style, low-rise, dual-plane intake. There's a very limited selection of tall-deck 400 intakes, compared to the many available 351C manifolds. Price Motorsport offers adapter plates to adapt 351C Cleveland intakes for use on 351M/400 blocks.

V-6 IN SunfireI own an '03 Pontiac Sunfire. I was wondering if it would be possible to swap out the stock 2.2L Ecotec for the later model Sunfire GT 3.1L V-6. Will this motor bolt right up, or will I have to modify the engine mounts? Will it bolt up to the automatic transmission? If you have any suggestions for an easier swap or similar motor as far as performance I would also greatly appreciate the feedback.
Theo Wendt
Hugo, MN

Anything's possible, but is it practical? Along with the Chevrolet Cavalier, Pontiac's Sunfire is a member of GM's third-generation J-body. Only four-cylinder engines were factory-installed in these cars. The '96-'02 Sunfire GT used the 2.4L (146ci) RPO LD9, a DOHC Quad-4 variant with twin balance shafts rated at 150 hp and 155 lb-ft. In '03, the Ecotec was introduced: Your 2.2L (134ci) Ecotec variant carries a 140hp/150 lb-ft rating.

RPO LG8 (VIN J), the modern version of the 3.1L (191ci) 60-degree V-6, is found in larger cars, typically the '00-'03 Pontiac Grand Prix SE and Chevy Malibu, the '01-'02 Chevy Lumina, and the '00-'05 Buick Century. Rated output ranged from 170 to 175 hp and 190 to 195 lb-ft. Although a solid, dependable grocery-getter, the pushrod 3.1L V-6 is nothing to write home about; the DOHC Ecotec has much more performance potential and hot rod parts availability.

Because the 3.1L V-6 was not offered stock in your chassis, custom fabrication skills would be needed to install it. Front-end weight with the V-6's iron block and aluminum heads would increase over your all-aluminum four-banger. The Ecotec and GM 3.1L V-6 have different trans mounting patterns, so your existing trans won't bolt up, either. As is the case with any late-model swap, a knowledge of wiring, electronics, and computer interface is needed. A typical cross-platform FWD (front-wheel-drive) GM swap involves grabbing the entire front engine and transaxle (aka the "powertrain assembly"), the front cradle, the computer, and the wiring harness from the donor vehicle, then trying to figure out how to graft all this into the receiver vehicle. You should have access to the complete factory service manuals and wiring diagrams for both vehicles.

In my opinion, this is way too much effort to gain a measly 30 hp. Instead, keep what you have and install a GM Performance Parts supercharger kit on the 2.0L engine (GM kit PN 17800003 fit the '03-'05 Cavalier and Sunfire). This will raise output over 200 hp without the need for a time-consuming, expensive engine swap. GM's kit includes all necessary hard parts, but your GM dealer still has to reflash the computer. There are also complete supercharged and turbocharged Ecotecs from later cars, but this could require the later wiring harness, fuel system, and computer. And most were only offered with a manual trans. For more information on hopping the Ecotec, see HOT ROD, July '07, "Ecotec to Go."

Blown ZZ4 Spark PlugsI am writing regarding the article about a supercharged GM 350 crate ZZ4 engine ("ZZ4 Power Boost," Mar. '09). I am putting this motor together the way the article was written, but I have come across one small problem: There is no such spark plug as the nonprojected Autolite No. 3935 you used. I want to put the motor together the way you did it. What is the correct plug?
Thomas First
St. Peters, MO

The supercharged motor needed a colder plug than those offered in Autolite's standard street series, so we used an Autolite race plug that may not be listed in its standard catalog: PN AR3935 has a 5/8-inch hex, 3/4-inch reach, and a gasket seat. If you can't find the plugs locally, Jegs sells them for $2.69 each (as of July 2009). Competitive alternatives include a Champion C63C or an NGK R5671A-7.

This table illustrates the theoretical changes in the torque and power outputs of typical small- and big-block Chevy engines due to an increase in stroke (cylinder-bore size remaining unchanged). The data are based on sophisticated computer modeling simulations conducted by Dave Ebbert at DNE Motorsports Development. Except as noted, all dimensional data are in linear inches.